Written by Cameron Fielden and Sina Khosravani
Lice: Disease vectors or only a nuisance?
In today’s world, having lice is generally just a nuisance. If you start feeling an itchy head, you can have someone check you for lice, then go to a local supermarket and pick up some over the counter delousing shampoo that is fairly inexpensive. Other than being socially taboo to have lice, having lice is treated as something that happens to school children that poses no risk to their health. This is likely due to the following statement from the Centers for Disease Control and Prevention (CDC). According to the CDC: “Head lice are not known to transmit any disease and therefore are not considered a health hazard.” However, there is very interesting research and evidence that the CDC’s official statement on head lice may not be correct.
Before 1928, the mechanisms by which lice transmit disease were not understood. This allowed lice contamination to become an epidemic from the turn of the 19th century to the early 20th century. Lice were considered to be disease vectors even before more concrete knowledge about the connections between lice and diseases was found.
London during the mid-to-late 19th century was a very dirty place that was contaminated with many diseases. For instance, between 1865-1867 the Cattle Plague was spreading all our London. The only way citizens of London combated this disease was to slaughter the cows once infected. This plague conveys how contaminated London was at the time and also how much knowledge they lacked about combating certain diseases.
We examined the Medical Officer of Health reports from 1848 (the inception of the Medical Officer of Health position) to 1928. Up to about 1910, the Medical Officer of Health reports would speak about the percentages of people with lice, how many houses were sanitized, and discuss how the lice spread. For example, in the Finsbury 1910 report, it describes how to get rid of lice on a woman’s baby they had to disinfect the bedding and fumigate the home. However, after 1910, many medical officers started to comment on the rise of disease alongside lice outbreaks. In the Walthamhow 1911 report, the medical officer reported that 7 boys under the age of 18 were found to have head lice, while 36 girls under the age of 18 had head lice. Also, in the Shoreditch 1911 report, 30 out 260 cases had contamination of either head or body louse. Another report from 1911 by the London County Council stated that 12 percent of girls had body lice, while 6 percent of boys had body lice. In the Edmonton 1916 report, nits (lice eggs) were found in approximately 425 boys and 1044 girls. Live lice were found on the hairs of 28 boys and 66 girls. Also, the Westminster 1916 report stated that there was a total of 234 cases of body lice (both genders), and a total of 159 cases of hair lice (both genders). The increase in number of lice cases seen in Edmondton and Westminster conveys that the spread of lice was happening rapidly. As early as 1909, in the London County Council 1909 report, the medical officer reports: “The autumnal high level in the flea and bug curves makes a comparison with the curves of diseases which have an autumnal prevalence.” Furthermore, in the Hackney 1912 report, the medical officer reports that the extent that lice play in spreading infectious diseases was unknown but it could be shown experimentally (Nicolle) that body louse could spread certain diseases. Continuing this trend, the London County Council 1911 report says that isolation is needed to stop the spread of disease in reference to lice or scabies. During WWI, flyers like the one below were distributed to British soldiers on the front line. This was likely due to the discoveries of the French researcher Charles Nicolle, whose work is described in the next section. The flyer emphasizes the concern the British government had for lice causing typhus.
In 1915, there was a pamphlet published by the London School of Hygiene and Tropical Medicine titled The Danger of Disease From Flies and Lice that outlined preventive and remedial measures when dealing with lice contamination. The pamphlet stated that, “It has for some time been suspected, and is now definitely known, that Typhus . . . is conveyed by lice.” The reader was informed that “the best preventive against lice is strict personal cleanliness.” The goal in lice prevention is to make sure that you are not providing an environment that promotes breeding of more lice, therefore, you must not give lice the environment it needs to survive and reproduce. The Danger of Disease From Flies and Lice gave two ways to prevent lice contamination: 1) frequently search underclothing (especially along seams and folds) for lice presence, if lice is found, dust clothes with a powder consisting of naphthalene, mixed with 2 percent iodoform and 2 percent creosote 2) use of a fine comb can help detach nits (lice eggs) from the hair. As soon as lice contamination has been detected, these steps should be taken: 1) (for head lice) all hair must be cut short, and should be rubbed down with a 2 percent solution of carbolic or with a tablespoon of malt vinegar in a cup of warm water 2) (for clothes lice) infected clothes should be put in boiling hot water, and a mixture of soft soap or Vaseline with petrol rubbed in. An additional soap can be made by mixing: soft soap (2 oz.), water (6.5 pints), and Jeyes’ fluid (1 teaspoon). This soap can be applied to the skin just like lotion.
A lot of the remedies mentioned in The Danger of Disease From Flies and Lice would now be considered ineffective. Also, most of these remedies such as napthalene, iodoform, and carbolic weren’t available in most households. These noneffective techniques led to the rapid spreading of lice. Before 1928 the science community didn’t understand how lice transmitted typhus into the body, although there was evidence that they did, and they weren’t clear on the best ways to stop the spread and transmission of lice. This lack of understanding was a factor in the spread of lice within England’s population in the early 20th century. There were no vaccines or medicines that could combat typhus. That is why the best way to stay clear of lice during those times required extensive personal cleanliness. People would need to comb their hair and change their clothing to prevent lice from colonizing them. The problem with these preventive techniques was that most of the population during early 20th century didn’t have the money/accessories to be able to constantly keep themselves clean. The majority of the population couldn’t afford to wear new pieces of clothing everyday. This population was working 12 or more hours a day at industrial sites that were contaminated with many germs and bacteria. Not only was there not enough knowledge about the mechanisms by which lice transmitted disease, but there was also a societal imbalance that could not provide care to the entire population.
1928 Nobel Prize for investigations into typhus
In 1928, Charles Nicolle was awarded the Nobel Prize in Physiology or Medicine. In Nicolle’s Nobel lecture, he retraced the events that occurred that led him to believe that lice transmit typhus, and the experiments he did to prove his hypothesis. The following image shows Charles Nicolle in his laboratory.
Upon arriving in Tunisia in January of 1903, Nicolle saw a few cases of typhus that flared up each winter in the rural districts of Tunisia. From these districts, it would spread to the doss houses, prisons, and outskirts of town. In June of 1903, Nicolle visited a native prison where there was a prison outbreak. By noticing that the people affected by the typhus in the prison were people who have touched prisoner clothing, he deduced that lice could be the only culprit. With this hypothesis, Nicolle set up experiments to try and infect a chimpanzee with typhus. The experiment was a success in June of 1909. Nicolle went on the prove that typhus in lice was not hereditary. Finally, Nicolle tried to develop a preventative vaccine for typhus but was unsuccessful. Nevertheless, his work in understanding the transmission of typhus through lice helped medical professionals understand how to prevent typhus before a vaccine was ever created. Nicolle’s work created a foundation of understanding on how lice contaminates certain populations.
The Medical Officer of Health reports barely mention lice after 1928. The only thing that is mentioned in the health reports is the number of lice cases treated, and the comments amount lice transmitting diseases are not made anymore. For example, the Willesden 1949 report says that: 30 children under 5 were treated for lice, 282 children aged 5-14 were treated for lice, and 81 adults (9 men, 72 women) were treated for lice. This shift from trying explain how diseases and lice are connected to just reporting the number of cases happened around the 1940s. This shift is likely because a vaccine for typhus was developed during WWII.
While government bodies have deemed lice to not be a public concern, some researchers still study the connection between lice and diseases. There is a website that lists research papers written about disease outbreaks that are thought to have been caused by a lice epidemic. These research papers range from 1928 to 2017.
While some researchers are still trying to find links between lice spreading different diseases, it is generally accepted by the public that lice are only a nuisance. The main disease that lice do transmit has now had a vaccine for 80 years. In modern times, lice are not considered a health hazard, they are more considered an inconvenience due to the itchiness and irritation they can cause on parts of the body. In summary, lice are disease vectors, but they have been reduced to a just a public nuisance due to the creation of a vaccine for typhus.
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